Sewer lines and waste treatment equipment frequently are subject to clogging by grease build up, especially in urban areas having a large number of restaurants.
Traditionally, sewer grease has been cleared using one of several methods. Grease interceptors have been employed to prevent grease from entering the sewer system in the first place; however they require proper installation and maintenance to be effective. Dawson et al., "Design and Operation of Grease Interceptors", J. Water Pollut. Control Fed., 16: 482 (1944).
Caustic chemicals, such as sodium hydroxide and emulsifiable chlorobenzene compounds have also been used over the years to prevent grease accumulation in sewers, however they have not been wholly successful. Lee, "How to Degrease Sludge Lines", Wastes Engineering, 30: 204 (1959). More recently, many other compounds have become commercially available for this purpose. In particular, a methylene chloride/mineral spirits mixture containing about 6% by weight methylene chloride, commercially available from Thero-Chem as T160, has been found to be a useful degreaser. Although, methylene chloride is a powerful degreaser, it is a known carcinogen, thereby limiting the usefulness of T160. In addition, T160 also damages pumping equipment, particularly pump seals, made of plastic, neoprene rubber, or butyl rubber. Such pump seals are used in the water trucks used to transport and spray cleaning agents into sewer equipment.
Manual removal of grease build up using rods and high pressure water hoses is also used. High pressure water streams may break up grease clogs and is certainly a non-toxic method of grease control; however water alone does not dissolve grease.